Combine sugar, flour and salt in a bowl.,Stir in lemon juice, rind, beaten egg yolks, butter and milk.,Beat egg whites until stiff but not dry.,Fold into lemon mixture.,______,Place in larger pan; pour hot water to about 1-inch depth.,Bake in 350° oven for about 40 minutes or until topping is set and golden brown.,Serve warm.,Makes about 4 servings.